Financing Arrangments-Interest (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Apr. 01, 2012
1% Sr. Convertible Notes due 2013 [Member]
Interest Cost Recognized For Convertible Notes
Contractual interest coupon	$ 2,319	$ 2,319
Amortization of bond issuance costs	696	696
Amortization of bond discount	14,058	13,025
Total interest cost recognized	17,073	16,040
1.5% Sr. Convertible Notes due 2017 [Member]
Interest Cost Recognized For Convertible Notes
Contractual interest coupon	3,750	3,750
Amortization of bond issuance costs	667	667
Amortization of bond discount	9,519	8,861
Total interest cost recognized	$ 13,936	$ 13,278